Evolution of order during vacuum-assisted self-assembly of graphene oxide paper and associated polymer nanocomposites

Three mechanisms are proposed for the assembly of ordered, layered structures of graphene oxide, formed via the vacuum-assisted self-assembly of a dispersion of the two-dimensional nanosheets. These possible mechanisms for ordering at the filter-solution interface range from regular brick-and-mortar-like growth to complete disordered aggregation and compression. Through a series of experiments (thermal gravimetric analysis, UV-vis spectroscopy, and X-ray diffraction) a semi-ordered accumulation mechanism is identified as being dominant during paper fabrication. Additionally, a higher length-scale ordered structure (lamellae) is identified through the examination of water-swelled samples, indicating that further refinements are required to capture the complete formation mechanism. Identification of this mechanism and the resulting higher-order structure it produces provide insight into possibilities for creation of ordered graphene oxide-polymer nanocomposites, as well as the postfabrication modification of single-component graphene oxide papers.